nutrients Review Are Fruit Juices Healthier Than Sugar-Sweetened Beverages? A Review Alexandra Pepin 1 , Kimber L. Stanhope 2,* and Pascal Imbeault 1,3,* 1 Behavioral and Metabolic Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N6N5, Canada; [email protected] 2 Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA 3 Institut du savoir Montfort, Hôpital Montfort, Ottawa, ON K1K0T2, Canada * Correspondence: [email protected] (K.L.S.); [email protected] (P.I.); Tel.: +1-530-752-3720 (K.L.S.); +1-613-562-5800 (ext. 7290) (P.I.) Received: 1 April 2019; Accepted: 29 April 2019; Published: 2 May 2019 Abstract: Free sugars overconsumption is associated with an increased prevalence of risk factors for metabolic diseases such as the alteration of the blood lipid levels. Natural fruit juices have a free sugar composition quite similar to that of sugar-sweetened beverages. Thus, could fruit juice consumption lead to the same adverse effects on health as sweetened beverages? We attempted to answer this question by reviewing the available evidence on the health effects of both sugar-sweetened beverages and natural fruit juices. We determined that, despite the similarity of fruits juices to sugar-sweetened beverages in terms of free sugars content, it remains unclear whether they lead to the same metabolic consequences if consumed in equal dose. Important discrepancies between studies, such as type of fruit juice, dose, duration, study design, and measured outcomes, make it impossible to provide evidence-based public recommendations as to whether the consumption of fruit juices alters the blood lipid profile. More randomized controlled trials comparing the metabolic effects of fruit juice and sugar-sweetened beverage consumption are needed to shape accurate public health guidelines on the variety and quantity of free sugars in our diet that would help to prevent the development of obesity and related health problems. Keywords: free sugars; fruit juices; fructose; high-fructose corn syrup; sugar-sweetened beverages; dyslipidemia 1. Introduction The ingestion of free sugars may favor the overconsumption of energy, thus promoting the development of risk factors associated with metabolic diseases such as hypertriglyceridemia, hypercholesterolemia, and insulin resistance [1–3]. Moreover, the current literature strongly suggests that ingestion of sugar-sweetened beverages increases the cardiometabolic risk and risk factors more than isocaloric amounts of complex carbohydrates [4]. Free sugars are defined as any types of simple sugars (monosaccharides or disaccharides) that have been added to beverages or food products during their transformation or preparation by food industries or by the consumer per se, plus sugars naturally present in fruit juices, fruit juice concentrates, honey, and various syrups [5]. Sugars that occur in the natural structure of entire fruits and vegetables as well as those from milk (lactose) are not categorized as free sugars [5,6]. Added sugars include sugars and syrups that are added during the preparation or the transformation of food and beverages. Therefore, natural fruit juices do not contain added sugars, but on the basis of the above definition, they are a significant source of free sugars. While it is mainly accepted that the overconsumption of sugar-sweetened beverages may lead to adverse effects on health [3,4], the evidence pertaining to the consumption of fruit juices is a matter of Nutrients 2019, 11, 1006; doi:10.3390/nu11051006 www.mdpi.com/journal/nutrients Nutrients 2019, 11, 1006 2 of 16 debate. This is reflected in the inconsistency between dietary guidelines that relate to the consumption of natural fruit juice. The World Health Organization (WHO) recommends reducing the intake of free sugars to less than 10% (and, ideally, less than 5%) of total daily energy intake, thus including sugars naturally present in fruit juices in the category of sugars whose consumption should be reduced. The 2015–2020 Edition of the Dietary Guidelines for Americans, a resource for health professionals and policymakers for the design and implementation of nutrition programs in the United States, recommends consuming less than 10% of calories per day from added sugars, thus not including sugars naturally present in fruit juices in the category of sugars whose consumption should be reduced [7]. However, the American Academy of Pediatrics recommends limiting the consumption of fruit juice for children between the age of 1 and 3 years to 4 oz (120 mL)/day, for those from 4 to 6 years to 4–6 oz (120–180 mL)/day, and for those from 7 to 18 years to 8 oz (240 mL)/day [8,9]. There are currently no data estimating the average consumption of free sugars in the United States. Still, fruit juices are commonly consumed on a daily basis by many American adults and children. This review aims to summarize the effects of free sugar consumption, especially from sugar-sweetened beverages, on metabolic health and to consider whether fruit juices may lead to similar health outcomes. 2. Added Sugars: Sucrose and High-Fructose Corn Syrup Simple sugars have been a part of the human diet for millennia. They were provided mainly by fruits and honey until white sugar (sucrose) became a common consumer product in the 19th century [10]. Nowadays, the worldwide consumption of sucrose is widespread, to the extent that it has tripled over the past 50 years [11]. In the United States, 77% of all calories purchased from 2005 to 2009 contained sweeteners, of which corn syrup, cane sugar, High-Fructose Corn Syrup (HFCS), and fruit juice concentrate were listed as the most commonly used [12]. Sucrose is naturally occurring in sugar cane and sugar beet and therefore extracted and purified directly from sugar cane or beet sap. In contrast, HFCS, which replaces sucrose in 40% of processed foods and beverages, is not naturally occurring [13]. In 1864, the Union Sugar Company generated corn syrup for the first time by treating cornstarch with enzymes to break down the complex carbohydrate into glucose and glucose polymers [14]. Although corn syrup was more affordable than basic cane or beet sugar, it tasted less than half as sweet as sucrose. The isomerization of corn glucose to fructose using microbial enzymes was discovered in the late 1950s by the Clinton Corn Processing Company [14]. This product was, however, not economically viable at that point, mainly because of its instability. Yoshiyuki Takasaki, a Japanese scientist from the Japanese Agency of Industrial Science and Technology, was the first to develop HFCS by isolating a heat-stable glucose isomerase (xylose isomerase) derived from Streptomyces sp. in the late 1960s [14]. HFCS can be labeled under many different appellations such as isoglucose or glucose-fructose. The increasing popularity of HFCS amongst food industries was principally due to a more favorable price (the USA being the world’s largest producer of corn) and to the fact that its liquid form both inhibits crystallization and helps to maintain the moisture content of baked goods [15], while also being easily diluted in sugar-sweetened beverages. A few years later, HFCS-55 (45% glucose, 55% fructose) was marketed, and HFCS largely replaced sucrose in sugary drinks made by major brands of cola beverages (1984) [14]. Amongst 43 countries from which the HFCS consumption per capita was analyzed in 2000, 2004, and 2007, the United States was ranked the highest with a yearly HFCS consumption of 24.78 kg/per capita [16]. Nevertheless, HFCS consumption has been steadily decreasing since 2009 in the United States, as opposed to sucrose consumption which tends to increase [17]. This observed shift in sweetener choice by the food industry is probably due to the fact that HFCS consumption has been badly publicized in the public media in recent years. The 2017 per capita supply of caloric sweeteners in the United States was estimated to be 158 g [17], of which 86 g was derived from sucrose (cane or beet sugar), 50 g from HFCS, and 22 g from glucose corn syrup, dextrose, honey, and other syrups [17]. The actual intake can be estimated by assuming losses due to spoilage and wastage of 11% at the retail and institutional level and of 20% by the consumer [18]. Nutrients 2019, 11, 1006 3 of 16 The sucrose molecule is composed of one unit of glucose covalently bonded to one unit of fructose, the fructose concentration of sucrose therefore being 50%. In contrast, glucose and fructose occur in their free forms in HFCS [19]. This makes it possible to vary the fructose-to-glucose ratio in the syrup mixture and create different formulations. According to the Corn Refiners Association, there are two primary compositions of HFCS which are HFCS-42 and HFCS-55, respectively produced with 42% and 55% of fructose [20]. HFCS-55 is considered as the most commonly used form amongst food industries, but there are currently no obligations for manufacturers to disclose what formulation of HFCS they use on the ingredient list of the food labels. Thus, the fructose content of most processed foods and sugar-sweetened beverages remains uncertain [21]. Ventura et al. (2011) measured the sugar content of 23 popular sugar-sweetened beverages purchased at the grocery store with a focus on fructose. The results from this study revealed that 15 of those beverages had a fructose-to-glucose ratio exceeding 55%, with a mean fructose content of 59%. Moreover, several renown-brand beverages appeared to be made with a formulation of HFCS containing 65% of fructose instead of 55% [21]. However, this study was criticized for the methods used, which were designed to identify sucrose, glucose, and fructose, but were not sensitive enough to precisely measure other traces of sugars (such as maltose) if they were present in the beverages [22].